The present invention relates to a method for manufacturing eclectic masks used in the photomechanical process, and more particularly to a method for eclectic mask preparation carried out by means of an image scanning recorder such as a color scanner.
In general, an eclectic mask (sometimes called also "cut mask" or "cutout mask") is used for many purposes such as making up a composite picture or image from, for instance, two photographs by using a part of either photograph, erasing backgrounds of photographs, partially adding or restraining exposure when taking a photograph.
Such eclectic masks have been manufactured heretofore by handicraft. For example, a transparent sheet is set on a photographic film laid on a light table, and a fine line is drawn on the sheet along the contour of a shape expressing a photographic theme such as a portrait or a trade sample. The inside or outside of the contour line drawn on the sheet is then painted out. In another handicraft technique, said fine line is drawn directly on the photographic film per se for directly painting out. It is however difficult and requires great skill to quickly draw the contour line with correctness in these manual works.
The applicant has already proposed some improvements in respect of the eclectic mask preparation wherein an image scanning recorder such as a color scanner is made use of for a convenient speedy manufacture of precise eclectic masks. One of said proposals is disclosed in the Japanese Patent Laying-open Gazette Sho. 54-29202 titled "An apparatus for making contoured images". The other proposal is disclosed in ibid. Sho. 54-36801 titled "A method for eclectic mask preparation".
These apparatus and method utilize, as a principal means, a quadratic differential operator that is well known in the pictorial image treatment technology as a measure for detection of pictorial image contours. Eclectic masks can be thus manufactured at real time without any handicraft. In the abovesaid apparatus, only the required contour of pictorial image is automatically picked up while in the abovesaid method there may be manufactured an eclectic mask with a contour line the inside or outside of which is "painted out" by means of its recording system for reproduction thereby making it unnecessary to paint out said inner or outer area in a subsequent process.